Heat exchanger

ABSTRACT

A heat exchanger having an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another to provide an integral support structure for the heat exchanger. The structural interconnection includes upper and lower structural members extending between the pair of vertical steam/water separators. The upper and lower structural members include headers, and an arrangement of heating surface which extends between and is fluidically connected to the headers. A structural support framework surrounds the heat exchanger for bottom support thereof, the framework providing structural support and rigidity for the heat exchanger and a means by which the heat exchanger can be picked up and lifted for placement at a desired location.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates, in general, to the field of heatexchangers and, more particularly, to a heat exchanger having anintegral support structure and a structural framework for the supportthereof.

The present invention employs the teachings of U.S. Pat. No. 6,336,429to Wiener et al., the text of which is hereby incorporated by referenceas though fully set forth herein.

To the extent that explanations of certain terminology or principles ofthe heat exchanger, boiler and/or steam generator arts may be necessaryto understand the present invention, the reader is referred to Steam/itsgeneration and use, 40th Edition, Stultz and Kitto, Eds., Copyright©1992, The Babcock & Wilcox Company, and to Steam/its generation anduse, 41st Edition, Kitto and Stultz, Eds., Copyright ©2005, The Babcock& Wilcox Company, the texts of which are hereby incorporated byreference as though fully set forth herein.

SUMMARY OF THE INVENTION

One aspect of the present invention is drawn to a heat exchanger fortransferring heat energy into a working fluid, such as water. The heatexchanger is used to transform at least a portion of the water from theliquid phase into saturated or superheated steam.

Vertical steam/water separating devices, disclosed in the aforementionedU.S. Pat. No. 6,336,429 to Wiener et al., are used to separate the steamfrom the steam-water mixture. A pair of such vertical steam/waterseparators, structurally interconnected and arranged as describedherein, provides an integral support structure for the heat exchanger.

The heat exchanger of the present invention is advantageously comprisedof an arrangement of heat transfer surfaces and fluid conveying conduitsarranged in a particular fashion to transfer a desired amount of heatenergy into the water. The heat transfer surfaces are advantageouslymade of tubes arranged into panels, and are provided with inlet andoutlet headers as required. As is known to those skilled in the art,heat transfer surfaces which convey steam-water mixtures are commonlyreferred to as evaporative or boiler surfaces; heat transfer surfaceswhich convey steam therethrough are commonly referred to as superheating(or reheating, depending upon the associated steam turbineconfiguration) surfaces. Regardless of the type of heating surface, thesizes of tubes, their material, diameter, wall thickness, number andarrangement are based upon temperature and pressure for service,according to applicable boiler design codes, such as the AmericanSociety of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section I, or equivalent other codes as required by law. Required heattransfer characteristics, pressure drop, circulation ratios, spotabsorption rates, mass flow rates of the working fluid within the tubes,etc. are also important parameters which must be considered. Dependingupon the geographic location where the heat exchanger is to beinstalled, applicable seismic loads and design codes are alsoconsidered.

The heat exchanger is bottom supported from a base which is part of anarrangement of interconnected rigid members that surrounds the heatexchanger and forms a structural support framework which, together withthe aforementioned integral support structure not only providesstructural support and rigidity for the heat exchanger, but also a meansby which the heat exchanger can be picked up and lifted for placement ata desired location. In the case of an application of the heat exchangeras a solar heat energy receiver, the structural support frameworkpermits the entire assembly of the heat exchanger and the framework tobe assembled on the ground and then lifted and set upon a tower duringinstallation. The structural support framework remains with the heatexchanger, thereby facilitating (if necessary) the removal of the heatexchanger from the tower should it become desirable to do so.

In accordance with the present invention, there is provided a heatexchanger comprising an arrangement of heat transfer surfaces and a pairof vertical steam/water separators structurally interconnected to oneanother and providing an integral support structure for at least aportion of the heat transfer surfaces of the heat exchanger. Thestructural interconnection includes upper and lower structural membersformed of heavy wall pipe and extending between the vertical steam/waterseparators. Each of the heavy wall pipes includes a pair of spaced innerpartition walls disposed in crosswise fashion to form a central portiontherein defining a header. The integrally supported portion of the heattransfer surfaces extends between and is fluidically connected to theheaders of the upper and lower structural members.

Each of the vertical steam/water separators includes four coplanarpedestal feet positioned at the lower end of the steam/water separator,and arranged at equally spaced intervals about the outer periphery ofthe steam/water separator.

The heat exchanger includes a structural support framework in the shapeof a rectangular parallelepiped having a top, a bottom and opposinglengthwise sides surrounding the heat exchanger for bottom supportthereof.

The bottom of the structural support framework is comprised of fourhorizontally extending parallel spaced lateral and longitudinal beamsintersecting one another to form a grid-like structure which includes alattice of obliquely-disposed web members positioned betweenintersecting longitudinal and lateral beams.

Two pairs of lateral braces intersect the inner two of the fourlongitudinal beams of the bottom of the structural support framework toform support bases for the vertical steam/water separators. The pedestalfeet of the steam/water separator are fixedly secured to the respectivesupport base.

Each of the opposing lengthwise sides of the structural supportframework has two pairs of parallel spaced vertical beams located atopposite ends of the structural framework and one pair of parallelspaced longitudinal beams intersecting the vertical beams and located atthe upper end of each of the opposing sides. A lattice ofobliquely-disposed web members is positioned between each pair ofvertical beams and the pair of longitudinal beams.

The top of the structural support framework is comprised of two lateralbeams intersecting the upper one of the pair of parallel spaced beamsextending along each lengthwise side. The two lateral beams are locatedabove the heat exchanger and provide a means by which the heat exchangerand the structural support framework can be lifted for placement at adesired location.

Another aspect of the present invention is drawn to the combination of aheat exchanger and the structural framework used for the supportthereof. The combination comprises an arrangement of heat transfersurfaces and a pair of vertical steam/water separators structurallyinterconnected to one another and providing an integral supportstructure for at least a portion of the heat transfer surfaces. Thestructural interconnection between the heat exchanger surfaces and thepair of vertical steam/water separators is comprised of upper and lowerheavy wall pipes, each pipe having partitions therein defining a centralheader. The integrally supported portion of the heat transfer surfacesextends between and is fluidically connected to the headers of the upperand lower heavy wall pipes. Each of the steam/water separators includesa plurality of pedestal feet positioned at the lower end of thesteam/water separator.

The structural framework part of the combination has a top, a bottom,and opposing lengthwise sides surrounding the heat exchanger for bottomsupport thereof. The bottom of the structural framework is comprised offour horizontally extending parallel spaced lateral and longitudinalbeams intersecting one another to form a grid-like structure andincludes a lattice of obliquely-disposed web members positioned betweenintersecting longitudinal and lateral beams. Two pairs of parallelspaced lateral braces intersect the inner two of the four longitudinalbeams at the bottom of the structural framework to form support basesfor the vertical steam/water separators whose pedestal feet are fixedlysecured to their respective support bases. Each of the opposinglengthwise sides of the structural framework has two pairs of parallelspaced vertical beams located at opposite ends of the structuralframework and one pair of parallel spaced longitudinal beamsintersecting the vertical beams and located at the upper end of each ofthe opposing sides. A lattice of obliquely-disposed web memberspositioned between each pair of vertical beams and the pair oflongitudinal beams. The top of the structural framework is comprised oftwo lateral beams intersecting the upper one of said pair of parallelbeams. The two lateral beams are located above the heat exchanger andprovide a means by which the heat exchanger and the structural frameworkcan be lifted for placement at a desired location.

These and other features of the present invention will be betterunderstood and its advantages will be more readily appreciated from thefollowing description, especially when read with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the heat exchanger which is shown, forclarity, without the structural support framework of the presentinvention;

FIG. 2 is an exploded perspective view of the heat exchanger illustratedin FIG. 1;

FIG. 3 is a perspective view of the pair of vertical steam/waterseparators structurally interconnected to one another to provide anintegral support structure in accordance with the present invention; and

FIG. 4 is a perspective view of the integrally supported heat exchangerstructure of FIG. 3, together with the structural framework used tosupport the heat exchanger structure in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will hereinafter be made to the accompanying drawings whereinlike numerals designate the same or functionally similar elementsthroughout the various drawings.

Referring to FIGS. 1-3, there is shown a heat exchanger 10 according tothe present invention. The heat exchanger 10 has left and right sidewalls 12, a roof portion 14, and a pair of vertical steam/waterseparators 16 of the type disclosed in the aforementioned U.S. Pat. No.6,336,429 to Wiener et al. The vertical steam/water separators 16 ofthis type are particularly suited to handle large transient swings inheat input to the heat exchanger 10 which may, in turn, cause largevariations in water levels within the steam/water separators 16. Theside walls 12 are comprised of panels of tubes having a welded membranebetween adjacent tubes. Welded membrane tube wall panels are well knownto those skilled in the art and will thus not be described in detailhere; for additional details, the reader is referred to theaforementioned Steam texts. The roof portion 14 is also comprised ofwelded membrane tube wall panels. While membrane wall tube panels aretypically employed in conventional industrial and utility furnace wallsto achieve a gas-tight construction, the provision of the membranebetween adjacent tubes in this application also provides for structuralrigidity of the panels and it is for that purpose that the side wallpanels 12 and roof portion 14 have a membrane wall construction.

If the heat exchanger 10 is used to provide merely saturated steam, theside walls 12 and roof portion 14 comprise evaporative or boiler heatingsurface. If the heat exchanger 10 is used to provide superheated steam,and as will be appreciated by those skilled in the art, some of theheating surface will have to be evaporative surface and other portionswill have to be superheater surface. In the embodiment shown in FIG. 1,the side walls 12 are evaporative or boiler surface, and may be providedwith inlet headers 18 and outlet headers 20. The steam-water mixturegenerated in tubes forming the side walls 12 is collected in the outletheaders 20 which also serve as a mix point to even out temperatureimbalances which may exist in the steam-water mixture. Stubs 22 on theoutlet headers 20 are interconnected via risers (not shown) to stubs 26on upper portions of each of the vertical steam/water separators 16. Thevertical steam/water separators 16 operate in known fashion (see U.S.Pat. No. 6,336,429 to Wiener et al.), separating the steam from thesteam-water mixture. If the heat exchanger 10 is designed for saturatedsteam production, steam outlet connections (not shown) from the topportions of each of the separators 16 convey the steam to its downstreamlocation and use. If the heat exchanger 10 is designed to producesuperheated steam, the steam is conveyed from the separators 16 tosuperheater surfaces for further heating and eventual collection andconveyance to its downstream location and use. Depending upon theinitial steam temperature and pressure, and the desired outletsuperheated steam temperature desired, the superheater may have to bedesigned as a multiple-pass superheater in order to provide adequatemass flux rates within the superheater surface tubes, and such conceptsare within the scope of the present invention. Two-pass, four-pass oradditional pass designs may be required, taking into account thetemperatures of not only the tubes in the superheater, but also thetemperature of the tubes in an adjacent structure, in order to addressdifferential thermal expansion concerns. In either case, the waterseparated from the steam-water mixture is conveyed to a lower portion ofeach of the separators 16, mixed with make-up feedwater, and conveyed tothe evaporative surface to start the process over again. In order tofacilitate the circulation of the water and water-steam mixturethroughout the heat exchanger 10, circulation pumps 28 mayadvantageously be provided at the lower portion of each of theseparators 16 for pumping the water back to the evaporative surface viasupplies (not shown).

Referring to FIG. 2, there is shown an exploded perspective view of theheat exchanger illustrated in FIG. 1. This view better illustrates therelationship between the side walls 12 and the integral supportstructure, generally designated 30, comprised of the pair of verticalsteam/water separators 16 structurally interconnected to one another bymeans of upper and lower structural members 32.

Referring to FIG. 3, there is shown a perspective view of the pair ofvertical steam/water separators 16 structurally interconnected to oneanother according to the present invention which provides the integralsupport structure 30 for the heat exchanger 10. The upper and lowerstructural members 32 are advantageously comprised of heavy wall pipe,rather than a structural I-beam or WF section, for reasons that willbecome apparent. One end of each member 32 is connected to one of thevertical steam/water separators, such as by welding. The structuralmembers 32 do not, in and of themselves, provide any direct fluidicinterconnection between the separators 16. The heavy wall pipe thatmakes up each of the structural members 32 is fitted with innerpartition walls 34 forming a central portion that comprises a header 36which performs a fluid collecting/conveying function. In addition toproviding an integral support structure for the heat exchanger 10, theheaders 36 which are part of the upper and lower structural members 32,are interconnected to one another by an arrangement of heating surface38 which extends between and is fluidically connected to the upper andlower headers 36. Typically, the heating surface 38 is up-flowingevaporative surface, comprised of tubes. Tube stubs 40 provideconnections for risers (not shown) which convey the steam-water mixtureto the tube stubs 26 on the separators 16 as hereinbefore described.

It will be noted that the heating surface 38 extends in between theheaders 36 of the upper and lower structural members 32 while providinga gap or space 42 between distal edges of the heating surface 38 and theouter wall of the steam/water separators 16. The side walls 12 extendinto this space 42, with the distal edges of the heating surface 38extending adjacent to and in close proximity with the inside portions ofthe side walls 12. However, in order to accommodate differential thermalexpansion the heating surface 38 is not connected to the side walls 12in any rigid fashion. The side walls 12 would be bottom supported from abase, in a fashion similar to that described below with respect to theintegral support structure 30. The sidewalls 12 may also be providedwith buckstays, not shown, which are well known to those skilled in theart as providing rigidity and support for membrane tube wallconstruction.

Referring to FIG. 4, there is shown a perspective view of a portion ofthe heat exchanger 10 according to the present invention, similar tothat illustrated in FIG. 1, together with a structural framework 50which supports the heat exchanger 10. For clarity, there is shown onlythe integral support structure 30 comprised of the pair of verticalsteam/water separators 16 structurally interconnected to one another bymeans of upper and lower structural members 32.

The three dimensional structural framework 50 is generally in a shape ofa rectangular parallelepiped and is defined by the top 51, the bottom52, and the lengthwise sides 55, and includes three sets of flangedbeams extending in the three mutually orthogonal directions, eightlongitudinal beams 58, six lateral beams 56, and eight vertical beams54.

The bottom 52 of the structural framework 50 is comprised of fourparallel spaced longitudinal beams 58 and four parallel spaced lateralbeams 56 which connectedly intersect one another to form a grid-likestructure. A lattice of obliquely-disposed web members 60 is positionedbetween the intersecting longitudinal and lateral beams 58 and 56 tostructurally reinforce the grid-like structure forming the bottom 52 andto stiffen or add rigidity to the structural framework 50.

The bottom 52 of the structural framework 50 includes a pair of supportbases 53, each being formed by respective pairs of parallel spacedlateral braces 57 connectedly intersecting the inner pair oflongitudinal beams 58. Each of the steam/water separators 16 includesfour pedestal feet 59 located at or near the bottom of the steam/waterseparator. The pedestal feet 59 extend outwardly from the steam/waterseparator wall at a substantially right angle, and are coplanar andarranged at equally spaced intervals about the outer periphery of thesteam/water separator 16. The pedestal feet 59 are each provided with areinforcing gusset 61 and are fixedly secured to the support base 53.

Each of the lengthwise sides 55 of the structural framework 50 iscomprised of two pairs of parallel spaced vertical beams 54 located atopposite ends of the structural framework 50, and one pair of parallelspaced longitudinal beams 58 located at the upper end of the sides 55and connectedly intersecting the vertical beams 54. A lattice ofobliquely-disposed web members 60 is positioned between each pair ofvertical beams 54 and the longitudinal beams 58 to structurallyreinforce the sides 55 and to stiffen the structural framework 50.

The top 51 of the structural framework 50 is comprised of two lateralbeams 56 which intersect and are connected to the upper one of each ofthe pairs of longitudinal beams 58 located at the upper end of thelengthwise sides 55. In addition to reinforcing the top 51 andstiffening the structural framework 50, the top lateral beams 56 aregenerally located over the heat exchanger 10 and provide a means bywhich the heat exchanger 10 and the supporting structural framework 50can be picked up and lifted for placement at a desired location.

Although the present invention has been described above with referenceto particular means, materials, and embodiments, it is to be understoodthat this invention may be varied in many ways without departing fromthe spirit and scope thereof, and therefore is not limited to thesedisclosed particulars but extends instead to all equivalents within thescope of the following claims.

1. A heat exchanger comprising an arrangement of heat transfer surfacesand a pair of vertical steam/water separators structurallyinterconnected to one another and providing an integral supportstructure for at least a portion of the heat transfer surfaces of theheat exchanger.
 2. The heat exchanger of claim 1, wherein the structuralinterconnection includes upper and lower structural members extendingbetween the vertical steam/water separators.
 3. The heat exchanger ofclaim 2, wherein the upper and lower structural members are formed ofheavy wall pipe.
 4. The heat exchanger of claim 3, including a pair ofspaced partition walls disposed in crosswise fashion within the heavywall pipe to form a central portion therein.
 5. The heat exchanger ofclaim 4, wherein the central portion is a header.
 6. The heat exchangerof claim 5, wherein said portion of the heat transfer surfaces extendsbetween and is fluidically connected to the headers of the upper andlower structural members.
 7. The heat exchanger of claim 1, including asupport structural framework having a top, a bottom and opposinglengthwise sides surrounding the heat exchanger for bottom supportthereof.
 8. The heat exchanger of claim 7, wherein the structuralframework is in a shape of a rectangular parallelepiped.
 9. The heatexchanger of claim 7, wherein the bottom of the structural framework iscomprised of horizontally extending lateral and longitudinal beams. 10.The heat exchanger of claim 9, wherein the lateral and longitudinalbeams intersect one another to form a grid-like structure.
 11. The heatexchanger of claim 10, including a lattice of obliquely-disposed webmembers positioned between intersecting longitudinal and lateral beams.12. The heat exchanger of claim 9, wherein the bottom of the structuralframework includes four parallel spaced longitudinal beams
 13. The heatexchanger of claim 12, including two pairs of parallel spaced lateralbraces intersecting the inner two of said four longitudinal beams toform support bases for the steam/water separators.
 14. The heatexchanger of claim 13, wherein each of the vertical steam/waterseparators includes a plurality of pedestal feet positioned at the lowerend of the separator and fixedly secured to a respective one of thesupport bases.
 15. The heat exchanger of claim 7, wherein each of theopposing lengthwise sides of the structural framework has two pairs ofparallel spaced vertical beams located at opposite ends of thestructural framework and one pair of parallel spaced longitudinal beamsintersecting the vertical beams and located at the upper end of each ofthe opposing sides.
 16. The heat exchanger of claim 15, including alattice of obliquely-disposed web members positioned between each pairof vertical beams and the pair of longitudinal beams.
 17. The heatexchanger of claim 7, wherein the top of the structural framework iscomprised of two lateral beams intersecting the upper one of said pairof parallel spaced beams.
 18. The heat exchanger of claim 17, whereinthe two lateral beams are located above the heat exchanger and providethe means by which the heat exchanger and the structural framework canbe lifted for placement at a desired location.
 19. In combination, aheat exchanger and the structural framework for the support thereof, thecombination comprising an arrangement of heat transfer surfaces and apair of vertical steam/water separators structurally interconnected toone another and providing an integral support structure for at least aportion of the heat transfer surfaces, the structural framework having atop, a bottom, and opposing lengthwise sides surrounding the heatexchanger for bottom support thereof.
 20. The combination of claim 19,wherein the structural interconnection is comprised of upper and lowerheavy wall pipes, each pipe having partitions therein defining a centralheader.
 21. The combination of claim 20, wherein said portion of theheat transfer surfaces extends between and is fluidically connected tothe headers in the upper and lower pipes.
 22. The combination of claim19, wherein the bottom of the structural framework is comprised ofhorizontally extending lateral and longitudinal beams intersecting oneanother to form a grid-like structure.
 23. The combination of claim 22,including a lattice of obliquely-disposed web members positioned betweenintersecting longitudinal and lateral beams.
 24. The combination ofclaim 22, wherein the bottom of the structural framework includes fourparallel spaced longitudinal beams.
 25. The combination of claim 24,including two pairs of parallel spaced braces intersecting the inner twoof said four longitudinal beams to form support bases for thesteam/water separators.
 26. The combination of claim 25, wherein each ofthe vertical steam/water separators includes a plurality of pedestalfeet positioned at the lower end of the separator and fixedly secured tothe respective one of the support bases.
 27. The combination of claim19, wherein each of the opposing lengthwise sides of the structuralframework has two pairs of parallel spaced vertical beams located atopposite ends of the structural framework and one pair of parallelspaced longitudinal beams intersecting the vertical beams and located atthe upper end of each of the opposing sides.
 28. The combination ofclaim 27, including a lattice of obliquely-disposed web memberspositioned between each pair of vertical beams and the pair oflongitudinal beams.
 29. The combination of claim 19, wherein the top ofthe structural framework is comprised of two lateral beams intersectingthe upper one of said pair of parallel beams.
 30. The combination ofclaim 29, wherein the two lateral beams are located above the heatexchanger and provide the means by which the heat exchanger and thestructural framework can be lifted for placement at a desired location.